1. Field of the Invention
This invention relates to friction stir welding tools. More specifically, the invention is a friction stir welding tool having at least one gimbaled shoulder contacting a workpiece.
2. Description of the Related Art
Many friction stir welding (FSW) apparatus utilize a welding tool that has two spaced-apart shoulders fixedly mounted to a welding pin that is rotated about its axis by the FSW apparatus. The two shoulders rotate with the pin and ride on the respective front and back (or top and bottom) of the workpiece being welded. If the thickness of the workpiece varies as the welding tool is moved therealong, the leading edge of one or both shoulders tend to dig into the workpiece which causes excessive weld flashing to develop along the weld.